Electrolytic etching device



p 1964 w. J. MONTGOMERY ELECTROLYTIC ETCHING DEVICE 2 Sheets-Sheet 1Filed Nov. 14, 1960 Maw INVENTOR 0 N f m w M? M w W L J p 22, 1964 w. J.MONTGOMERY 3,150,063

ELECTROLYTIC momma DEVICE Filed Nov. 14. 1960 2 Sheets-Sheet 2 IWill/I10 IN VEN TOR.

. y BY W/'///ZIm J Mo/nfqame/y A TTORNEYS' United States Patent3,350,968 ELECTRGLYTIC ETCHHNG DEVECE William 3. Montgomery, IUD. 4,Benton, Pa. Filed Nov. 14, 1960, Ser. No, 69,138 13 Claims. (Ci.Mid-224) This invention relates generally to the art of etching and isdirected particularly to improvements in apparatus for effecting theetching of metal by electrolytic action.

A presently employed procedure for applying letters, numbers, designs,code markings and the like to metallic surfaces by electrolytic actioninvolves the use of stencil tapes which are moistened with a suitableelectrolyte and are then placed upon an electric current conducting bodybeneath a frame which outlines the character to be etched and themetallic body is then placed over and upon the frame and a low amperageelectric current is caused to pass through the supporting body throughthe moistened stencil and into and through the metal body so as toefiect the transfer of the character to the surface of the metal body.This procedure has many undesirable features associated with it, amongwhich are that the operator is required to pick up the moistened stenciltape and place it in the correct position beneath the frame and upon theunderlying current conducting support, which is in the form of a carbonblock, holding the ends of the tape in his hands while moving it to theproper position under the frame.

The tape in the wet condition is awkward to pick up and will twist andbecome wrinkled so that the operator has difficulty in getting it in theproper position. In addition, having to handle the tape moistened orsaturated with the electrolyte, the operators hands and fingers are atall times wet with the electrolyte.

It is a particular object of the present invention, in view of theforegoing, to provide a new and novel apparatus whereby metallicmaterial may be etched by the use of conventional tapes, wherein theoperator is able to position the stenciling tape properly upon thesupporting carbon block and moisten the tape with the requiredelectrolyte and carry out the etching operation, without having tohandle the wet tape and without getting the elec' trolyte on his hands.

A further object of the invention is to provide apparatus for carryingout an etching operation by the employment of electrolyte moistenedstencil tape wherein means is provided for maintaining the tape in adesired taut condition across the carbon supporting block and whereinmeans is also provided for effecting the longitudinal shifting of thetaut tape so as to bring selected characters into proper position fortransfer by electrolytic action to a metal body.

Still another object of the invention is to provide an apparatus formaintaining a stencil tape in a straightened out, taut condition acrossthe top of the current conducting carbon body as above set forth,wherein the tape holding and supporting means may be adjusted to applyjust the right amount of tension to the tape and wherein means isprovided for supporting the adjustable tape tensioning means so thatsuch means with the tape may be moved as a unit with respect to thecurrent conducting block over which the tape lies.

A still further object of the invention is to provide a new and novelmeans for adjustably securing to a suitable support, the currentconducting carbon block through which the current is passed to andthrough the tape and into the body to be etched, whereby the carbon bodycan be shifted as desired transversely of the tape supporting means soas to bring the supporting means for the tape and the supporting meansfor the carbon block into a proper cooperating relationship.

3,150,068 Patented Sept. 22, 1964 The invention will be best understoodfrom a consideration of the following detailed description taken inconnection with the accompanying drawings forming a part of thisspecification with the understanding, however, that the invention is notconfined to a strict conformity with the showing of the drawings but maybe changed or modified so long as such changes or modifications mark nomaterial departure from the salient features of the invention as definedby the appended claims.

In the drawings:

FIG. 1 is a View in side elevation of apparatus constructed inaccordance with the preferred embodiment of the present inventionshowing the apparatus mounted upon and secured to a supporting table orthe like.

FIG. 2 is a view in top plan of the apparatus.

FIG. 3 is a longitudinal section taken substantially on the line 33 ofFIG. 2.

FIG. 4 is a sectional view taken substantially on the line 4-4 of FIG.3.

FIG. 5 is a top plan view on an enlarged scale of the central portion ofthe apparatus.

FIG. 6 is a sectional view taken substantially on the line 6-6 of FIG.5.

FIG. 7 is a perspective view illustrating a modified mounting for thecarbon block for facilitating vertical adjustment of the same.

FIG. 8 is a detail view illustrating another mounting for the carbonblock by which the latter may be vertically adjusted.

The invention broadly contemplates the provision of at least one pairand possibly several pairs of spaced clamps which are positioned onopposite sides of a carbon block or other suitable supporting meansthrough which an electric current may be passed and over and upon thetop of which the stencil tape is supported. The stencil tape is securedat its two ends in these clamps and the clamps are in turn supportedupon a slide or carrier suitably guided whereby it can be givenrectilinear movement so as to shift the supported clamps and efiiect thelongitudinal movement of the stencil tape across the current conductingcarbon supporting block.

Means is also provided whereby the clamps are adjustably held upon thecarrier slide, to be moved or adjusted longitudinally of the slide so asto apply desired tension to the stencil tape.

The tape clamps are of novel construction whereby the ends of the tapecan be easily and quickly placed in position and secured and in additiona novel means is provided for clamping the carbon block base in such away that it can be readily shifted or adjusted transversely of the lineof movement of the clamp supporting slide and the stencil tape.

The drawings illustrate a preferred embodiment of the apparatus whereinthere is provided an elongate slide box which is generally designated 10and which is here illustrated as supported upon and secured to asuitable sup porting structure generally designated 12, such as a worktable or the like.

The slide box is here illustrated as providing guide ways for two slidemembers and accordingly a two slide member structure will be described,although it is to be understood that the invention is not limited byreason of such description since an apparatus may be employed havingonly a single slide member and slide box or guide means or a slide boxor guide means may be provided for carrying any desired number ofslides.

The slide box illustrated is of substantial length as shown andcomprises the bottom 14, upstanding longi- 0 tudinal side walls 16 andend walls 18.

For maintaining the box in position the bottom 14 is provided adjacentto its ends with suitable apertures for c.) the extension therethroughof securing screws 2t for engagement into the underlying table 12. This,of course, is only one of any number of ways that the box may be securedin working position and, of course, is not intended to be in any waylimiting.

The slide box is here shown as having two spaced parallel guides 22which are formed by providing the thin longitudinally extending divisionwall 24 spaced centrally between the side walls 16 and engaged at itsends in the vertical slots 26 formed in the inner faces of the end wallsas best seen in FIG. 2.

Each of the guides 22 has positioned therein for longitudinal movementthe elongate slide bar 28. This slide bar, while of substantial length,is materially shorter than the guide 22 and is located so that it mayhave a substantial degree of longitudinal movement therein.

To facilitate the smooth longitudinal movement of the slide bar, eachend thereof is recessed as at 30 and in each recess is mounted on atransverse pivot pin 31, a roller member 32.

The slide bar 28 supports a pair of tape clamps, each of which isgenerally designated 33. The support for the clamps on their respectiveslide bars is such that the clamps may be readily shifted longitudinallyof the slide bar while maintaining a proper central position thereon.

A preferred method of supporting the clamps 33 upon their respectiveslide bars so that they can be adjusted and maintained in properalignment therewith comprises a rib or tongue '34 which engages in aslot in the clamp in the manner about to be described.

The clamps 33 are mounted upon the slide bar in pairs and each clampcomprises the body 35 of approximately the same Width or thickness asthe slide bar upon which it rests and each of the bodies includes arearwardly extending portion or tail piece 36 and a forwardlyprojectir'ig portion 37. The body 35 of each clamp has a tonguereceiving groove 38 in the bottom edge thereof which groove extends intothe tail piece 36. The forwardly extending portion 37 of the clamp liesabove the tongue of the supporting slide bar as is clearly shown in FIG.3.

The tail portion or tail piece 36 of each clamp has a longitudinal slot39 therein which slot opens through the top and bottom portion of thetail piece and this slot receives or has extended therethrough aclamping bolt 4-0 which is threaded into a bore 41 in the underlyingslide bar 28. The slot 39 is of a width greater than the diameter of thebolt so that when the bolt is loosened by being threaded outwardly inthe bore 41 the head of the bolt will rise from the top of the tailpiece and the clamp may then be shifted longitudinally on the slide barwithin the limits of the longitudinally extending slot 39.

Each clamp body 35 has formed therein from the top the drilled andtapped hole or bore 42 in which is threaded a pin 43 which functions asa handle for facilitating the sliding adjustment of the clamp. This pinmay be of metal or of any other suitable material which will serve thedesired function.

The forwardly extending or inwardly extending portion 37 of each clampbody has cut therein and transversely thereof the angulated slot '44,the inner end of which opens into a transverse drill hole 45 for thepurpose hereinafter described. As shown this angulated slot 44 comprisesan inner end portion a and the forward angularly extending entranceportion 12. The slot 44 is formed of gradually increasing width, beingnarrowest in its outer end b, which end opens through the inner face ofthe clamp body portion 37 close to the top of such portion and graduallyincreasing in width toward the transverse bore or hole 45. Also as isshown, the portion b of the slot slopes downwardly from the top of thebody portion 37 of the clamp, for a desired distance and then continuesinto the portion a which is substantially horizontal. Thus there isprovided by the slot 44 a flexible tongue portion 46 which is adapted tobe drawn down into clamping engagement with an end of a stencil tapeinserted into the open end of the slot portion 12 in the manner about tobe described.

The tongue 4-6 of the clamp is drawn down by a headed bolt 47, the shankportion of which is extended downwardly through the oversize bore 48 forthreaded engagement in the drilled and tapped bore 49 in the part of theclamp body 37 below the tongue.

In referring hereinabove to the Width of the angulated slot 44,reference is had to the spacing between the top and bottom surfaces ofthe slot and not to the distance of the slot from one side of the clampbody portion 37 to the other. It will, of course, be understood that theclamps 33 may be formed of any material suitable for functioning asdesired in this apparatus, preference being had for the plastic Luciteas this is not only uneffected by moisture of any kind and particularlyby the electrolyte used with the apparatus, but it also gives a pleasingappearance in the structure. Lucite is also of a character which willprovide necessary flexibility for the small bending or flexing movementof the tongue 46 when the head of the bolt 47 is drawn down to clamp anend of a stencil tape in the portion 1) of the clamping slot.

The bore or passage 45 is formed transversely through the clamp body toreduce the possibility of the plastic material breaking or cracking whenthe tongue is flexed.

It is also preferred that the slide bar 28 be formed of the same type ofplastic above referred to. However, it is to be understood that whilethis type of plastic is preferred, it is not intended that by specifyingplastic generally or the specific type named, there is any intention tolimit the invention to the use of these materials, since it will beapparent that there are other mateials which would function efliciently.

The numeral 54) generally designates the stencil tape which carries anumber of characters of any desired form or type which may be desired toapply to a metal body. Such characters are here illustrated as being inthe form of letters of the alphabet, designated 51 but it is to beunderstood that such characters may be numbers, code characters orspecial designs. This type of stencil tape used in electrolytic etchingis of standard and well known character. Accordingly, no detaileddescription of the same is believed to be necessary to an understandingof the operation of the present invention.

The tape 50 when put into use is connected between a pair of clamps 33which are mounted upon a slide 28 and the ends of the tape are securedto the clamps by being extended into the open ends of the clamp slots 44and then secured down by the flexible clamping tongues 46.

interposed between the inner portions 37 of the pair of clamps betweenwhich the stencil tape is held is the electrode unit and supportingbase, which electrode unit is generally designated 52 and the supportingbase is generally designated 53.

The electrode unit 5.2 comprises a body of electrically conductivematerial which is conventionally in the form of a carbon block body 54.

The electrode base 53 is preferably in the form of a rectangular body orplate 55 formed of Lucite or other suitable plastic or othernoncorrosive material upon the top of which the electrode 54 is securedin the manner about to be described.

The electrode base extends across the guide or guides 22 above andspaced from the top or tops of the underlying slide bar or slide barsdepending upon whether there are one or more, in the following manner.Means is provided for the support of the base 53, which means in thepresent instance consists of the side walls 16 of the slide box 15).Each side wall is formed or provided with a long recess 56 in the topedge thereof in which the electrode base positions and one end of eachof the two recesses 56 in which the base is supported, is undercut asdesignated at 57 while the opposite end of the recess preferably isvertical as indicated at 58.

The body 55 of the electrode base has its opposite longitudinal or sideedges beveled as indicated at 59 and one of these bevels corresponds inits angular disposition with the angle of the undercut end 57 of therecesses 56 so as to form the conventional dovetail connection betweenthe walls of the box and the base. The opposite longitudinal bevelededge of the electrode base body 55 may be of the same slope or angle asthat engaging the undercut end 57 of the slot and this other beveledside of the base is engaged by a pair of clamp bars 60, each of which isadapted to position in the recess 56 between the straight or verticalend 58 and the adjacent beveled side of the base body 55. Each of theseclamp bars has its inner end beveled or sloped as indicated at 61 andthe bars 60 are of a length slightly greater than the length of the openspace between the vertical end 58 of the recess and the adjacent side ofthe base body and the clamping bars are secured in clamping positionagainst the base body 55 by screws 62 which extend downwardlytherethrough through oversize holes or bores for threaded engagement inthe bottom of the recess 56. Since the clamping bars 60 are of suchlength that they cannot be drawn down flat onto the bottom of the recess56, it will be seen that they will apply a camming action against thebase body 55 to force the opposite side thereof into engagement with theundercut face 57 and the base body will thus be held against shiftingmovement transversely of the box walls as Well as against movement outof the recesses.

The carbon electrode block 54 is of rectangular form and is disposedupon the top of the base body 55 with its long sides parallel with thebeveled longitudinal sides 59 of the base body as is clearly shown inFIG. 5. This carbon electrode block is positioned upon a copper terminalplate 62 which rests upon the base body 55 as shown in FIG. 6 and aportion of this plate is extended beyond one end of the electrode blockforming the terminal tongue 63 which carries a binding screw 64.

The carbon electrode block 54 is provided with suitable vertical bores65 for extension therethrough of securing bolts 66 which pass throughaligned openings in the terminal plate 62 and into tapped and threadedopenings 67 in the base body 55 as shown in FIG. 6.

At the opposite end of the electrode block 54 from the terminal tongue63, the base body 55 has secured thereto the lower end portion 63 of aspring terminal which is generally designated 67. This spring terminalis of substantially C shape and stands vertically with the rounded topportion 69 thereof normally at a substantial elevation above the top ofthe terminal block 54. The bottom portion 66 of this terminal is securedto the base body 55 by the headed bolt 7%) which is threaded into thedrilled and tapped opening 71 in the base body as shown in FIG. 6.

The carbon electrode block 54 has the top surface thereof transverselycurved or arced as indicated at 72, the arc of curvature extending fromone long side of the block to the other as shown in FIG. 3 and thisarcuate or curved top surface had secured thereon a pad '73 of asuitable absorbent material to retain a suitable amount of electrolytefor establishing the necessary electrolytic action and conduction ofcurrent from the carbon electrode block to a metal body placed upon thetop of the pad.

Any suitable means may be employed for securing the absorbent pad to thetop of the carbon block 54, such means here being illustrated ascomprising an elastic band 76 or the like extending around the top ofthe block and across end portions of the pad which are extendeddownwardly along the ends of the block as shown in FIG. 6. Overlying theabsorbent pad 73 is a sheet of waterproof or non-absorbent materialwhich is generally designated '74 and which has one or more openings orcutout portions therein forming a window or windows 75 beneath which thecharacter carrying tape passes as shown in FIG. 5. These windows are ofsufiicient size to disclose the entire character which is to be etchedon the metal base.

Since the electrolyte liquid is applied to the absorbent pad tofacilitate carrying out the etching process, there is a possibility ofan excess of the electrolyte running down onto the surface of the carbonelectrode base body 55 and in order to prevent this excess material fromflowing into the box or onto the surface to which the apparatus issecured, the top of the body 55 is provided along each longitudinal sidewith a gutter slot 77 to carry off beyond the outer sides of the box anyof the liquid entering therein.

Any suitable means may be employed for securing the waterproof shieldsheet 74 in place upon the top of the absorbent pad but the means hereillustrated comprises carrying the ends of the sheet down along the endsof the carbon block in the same manner as the ends of the absorbentstrip 73 are placed and securing the ends of both of these pieces ofmaterial by the hereinbefore referred to elastic band 76 as illustrated.

In the operation of the apparatus it is conventional to use a suitablepower pack for transforming AC. to D.C., where an AC. source ofelectricity is employed for supplying the electric current, so as toobtain the necessary low amperage. Since the electrical system in whichthe apparatus is used forms no part of the invention no illustration ofthe same has been given or is believed to be necessary.

The terminals 63 and 67 have merely been illustrated with portions ofelectric current conductors 63a and 67a attached thereto through whichcurrent is supplied on one side to the carbon electrode body 54 and inthe performance of the etching operation the circuit is completed by theapplication of the metal body to be etched upon the top of the windowedabsorbent pad cover 74 and in contact with the resilient terminal 67.FIGS. 5 and 6 show in broken outline a body which is designated M, whichis representative of any metal body such as a metal tool or the likewhich is to have a character etched into the surface thereof. When thepad 73 is suitably saturated with the electrolyte by having a few dropsthereof deposited thereon through the window opening or openings and themetal body M is placed over the window openings to contact the wet padand the resilient terminal 67, then the direct current charge will flowthrough the terminal box 54 to the metal body through the circuitcompleting electrolyte to effect the transfer to the metal body of thesymbol exposed in the tape through the window opening '75.

It will, of course, be obvious that if any single letter, number orother symbol is to be applied to the metal body, only one tape need beused, but if a pair of letters, numbers or other characters are to beapplied to the body, then two or more tapes may be used and, of course,the number of window openings will be increased to correspond with thenumber of tapes and the number of symbols to be etched in side-by-siderelation in the metal body.

FIGS. 7 and 8 illustrate two modifications of the supporting means forthe carbon electrode block, which permit the block to be verticallyadjusted. With these vertical adjustments in association with the meansfor moving the carbon block supporting base transversely of the tapes itwill be seen that the flexibility of the apparatus is greatly increasedsince the height of the carbon block can be adjusted as may be desiredto obtain the best results in the operation of the apparatus.

In FIG. 7 the carbon block is generally designated 78 while theunderlying supporting base is generally designated 79. The block issupported upon the base 79 by a U-braclret which is generally designated8% and which comprises the bottom plate portion 81 and the upstandingparallel arms 82. These arms 82 are provided with vertical slots 83. Theplate portion 81 of the bracket is secured to the base 79 by bolts 84.The carbon block is positioned between the upstanding arms 82 of thebracket and it is provided with a suitable longitudinal bore 85 to haveextended therethrough the shank portion of a headed bolt as which alsoextends through the slots as shown so that the head of the bolt engagesthe outer side of the one upstanding arm $2 While the the opposite endof the bolt which is screw threaded extends through the slot in theopposite arm to receive a wing nut 87 which, when threaded onto thebolt, bears against the adjacent arm and effects the tightening of thearms against the block. With this arrangement it will be seen that byloosening the wing nut the carbon block may be raised or lowered asdesired.

In FIG. 8 the means for vertically adjusting the carbon block consistsin providing the base body 83 upon which the carbon block 39 is mounted,with four drilled and tapped bores 90 extending vertically therethrough,two at each end of the body es and directed toward the bottom of therecess 91 of the underlying box side wall 92. Adjusting bolts 93 arethreaded downwardly through the bores 99 for engagement with theunderlying bottom of the channel.

While FIG. 8 illustrates only two of the adjusting bolts 93 positionedfor engagement with the bottom of the recess 91 with one side wall 92 ofthe box, it will be understood that the opposite side wall carries acorresponding recess which has the bottom thereof engaged by a similarpair of adjusting bolts at the other end of the body 88. Each of therecesses 91 also has placed therein a clamping bar 94- correspondingwith the previously described clamping bars 69, the inner end of whichbar 94 rests against the beveled side of the adjacent carbon blocksupporting body 88 in the manner shown and the bar being secured inplace by screws 95 passing downwardly therethrough into the bottom ofthe recess 91.

As will be readily apparent, when the clamp bars 94 carried by the sidewalls of the box in the recesses thereof are loosened so that theirinner or beveled ends can be raised, then by properly turning the fouradjustment bolts 93, two only of which are shown as above explained, thecarbon supporting base 38 may be elevated to the desired extent and theclamping bar then resecured by screwing down the holding screws 95.Lowering of the carbon block supporting base would, of course, involvethe reversal of this operation by turning the bolts 93 in the properdirection and then following up the base by the clamping bars, byscrewing or turning down the securing screws 95.

It will be obvious from the foregoing that in setting up the tapes foroperation of the apparatus one end of the tape is secured in one clamp33 and the other end is then threaded between the absorbent pad 73 andthe overlying windowed sheet 74 and then carried on to the other clampwhere it is secured in the manner hereinbefore described. Any slack inthe tape may be taken up by loosening one of the clamp bolts 4% andshifting that clamp away from the other clamps so as to draw the tapetaut after which the bolt 4% is tightened down to hold the clamp inadjusted position on the slide bar 28.

The tape after being placed in position as described may then be shiftedlengthwise across the carbon electrode by moving the entire slide bar 28and the clamps thereon so as to progressively bring the letters or othercharacters into position for exposure through the window opening 75beneath which the tape lies.

In. setting forth the present invention reference has been made to theuse of a stencil tape and electrolyte eases for carrying out the desiredetching operation. No spev cific type of electrolyte is herein setforth, however, first for the reason that the electrolyte itself formsno part of the invention and secondly for the reason that in this 3 typeof etching diiferent electrolyte formulas must be used according to thetype of metal to be etched.

In addition to the foregoing the stencil tape has only been generallyreferred to. Here again, the tape forms no part of the invention sincesuch tapes are of well known character. These tapes or stencils are madeac cording to special processes and are of high dielectric value throughwhich the electrolyte fluid contacts the part to be marked. In carryingout the process a low amperage, low voltage current passes through theelectrolyte to electrically dissolve out the metal in the shape of thecharacters in the stencil to the desired depth in a mater of seconds.The mark is made without stress, strain or deformation of the mostprecise metallic surface. The process is similar in many respects toelectroplating, except that polarity is reversed so that metal isremoved from the part being marked, rather than depositing metal as inplating.

While in the illustration and description of the invention reference hasbeen made to the rollers 32 for supporting the slide bar or bars andthis construction is preferred, nevertheless it is to be uncerstood thatthe invention will function satisfactorily by having the bars 28 restfiat upon the bottom 14 of the box to slide thereon and therefore it isto be understood that the invention is not limited to the use of therollers in question.

It will be seen from the foregoing that the present invention provides arelatively simple but highly effective means whereby the stencil tapecan be easily and efficiently handled or manipulated without requiringthat the operator handle the tape to the extent that is necessary at thepresent time in following out the presently employed procedure and alsowithout requiring that the operator get the electrolyte on his hands. Bymaintaining the tape in the proper degree or" tightness across the topof the carbon electrode block the tape can be readily shifted asrequired to accurately bring the desired symbol or character intoposition for exposure through the masking window.

I claim:

1. In apparatus for electrolytically etching metal by use of anelectrolyte moistened stencil character carrying tape lying across thetop of a carbon electrode from which electric current is caused to passthrough the stencil tape to a metal body lying thereon, spaced clampingmeans each formed to provide cooperating jaws for gripping an end of aflexible stencil tape lying on and across the electrode, said meansbeing relatively adjustable for drawing the tape to a taut condition,means for moistening the tape in the part thereof lying on theelectrode, and means for reciprocably rectilinearly moving said clampingmeans and tape relative to the electrode for selectively positioningstencil characters on the tape relative to the top of the electrode,whereby an operators hands may be kept free for positioning a metal bodyupon the tape and electrode for stenciling and also kept free of contactwith the electrolyte.

2. Apparatus according to claim 1 for electrolytically etching metal byuse of an electrolyte moistened stencil character carrying tape lyingacross the top of a carbon electrode from which electric current iscaused to pass through the stencil tape to a metal body lying thereon,wherein the said means for moistening the tape consists of anelectrolyte absorbent body supported upon the top of the electrode.

3. Apparatus for selectively etching metal through an electrolytemoistened stencil tape, said apparatus comprising in combination with anelectrode body upon which a moistened stencil tape is placed for thepassage of electric current therethrough from the body into a metalelement placed on the top thereof, a supporting base for said electrodebody, a pair of spaced clamptmembers having said electrode body spacedtherefrom and interposed therebetween, said clamp members being adaptedto grip the ends of and hold taut a stencil tape extending across andengaging the electrode body, and means for moving the clamp members anda tape connected therebetween as a unit relative to the electrode body,the said means comprising a slide member beneath and supporting saidclamps.

4. Apparatus for selectively etching metal through an electrolytemoistened stencil tape, said apparatus comprising in combination with anelectrode body upon which a stencil tape is placed to be moistened withan electrolyte for the passage of electric current therethrough from thebody into a metal element placed on the top thereof, an elongatesupporting base having said electrode body mounted thereon, a pair ofbodies, means supporting the bodies on the base in spaced relation onewith the other and having said electrode body positioned therebetweenand in spaced relation therewith, means for securing to said spaced pairof bodies the ends of a stencil tape and for supporting the tape at anelevation to lie on and across the top of the electrode body, means forrelatively adjusting said pair of bodies on the supporting meanstherefor to draw into a taut conditon a tape connected therebetween, andmeans connecting the said supporting means for the pair of bodies forshifting the bodies as a unit together with a tape connectedtherebetween relative to the electrode.

5. In apparatus for carrying out an electrolytic etching operation onmetal wherein use is made of a stencil tape through which electrolytefluid contacts a part to be etched, a carbon electrode, a supportingbase for the same, means for connecting said electrode with one side ofan electric circuit, an electric terminal supported on the base adjacentto the electrode for connection with the other side of such circuit, anelectrolyte absorbent body supported by said electrode, a pair ofmembers disposed in spaced relation and having said electrode locatedtherebetween, means forming a part of each of said members for securingto each member an end of a stencil character carrying tape, said membersbeing adapted to support a tape connected therebetween at an elevationto pass over and in contact with said absorbent body, an elongate memberdisposed beneath and supporting said spaced members, means for movingsaid elongate member rectilinearly, and means for adjusting thepositions of said pair of members relative to one another and withrespect to the elongate supporting member whereby a stencil carryingtape may be drawn into a relatively taut condition across and in contactwith the absorbent body.

6. The invention according to claim with a guide means for said elongatemember for maintaining the latter against lateral movement during itsrectilinear movement.

7. The invention according to claim 5 with means for adjustably shiftingsaid carbon electrode supporting base transversely of the said pair ofspaced members.

8. The invention according to claim 5 with means for effecting thevertical adjustment of said carbon electrode.

9. In apparatus for carrying out an electrolytic etching operation onmetal wherein use is made of a stencil tape through which electrolytefluid contacts a part to be etched, a carbon electrode, a supportingbase for the same, means for connecting said electrode with one side ofan electric circuit, an electric terminal supported on iii the baseadjacent to the electrode for connection with the other side of suchcircuit, an electrolyte absorbent body supported by said electrode, aslide bar, a pair of relatively flat bodies disposed on edge and inspaced rela tion longitudinally of and upon said bar, means forming aguide channel lying below said electrode supporting base and having saidbar positioned therein for longitudinal movement, means whereby at leastone of said bodies may be adjusted on and longitudinally of the slidebar relative to the other body, means for securing said one body inadjusted position on the slide bar, means supporting said base betweenand in spaced relation to said bodies above the slide bar, and meanswhereby an end portion of a stencil tape may be releasably secured toeach of said bodies at an elevation to extend across the top of thecarbon electrode block, said last means comprising a slot formed in eachof said bodies from an end thereof adjacent to the carbon electrode bodywhereby a portion of the body above the slot forms a flexible grippingtongue and means for efliecting the flexing of the gripping tonguerelative to the lower part of the slot whereby to secure in the slot anend of the stencil tape.

10. The invention according to claim 9, wherein the said means forsupporting the electrode base comprises a pair of upstanding spaced andparallel wall members in the top edge of each of which a recess isformed, said base resting in said recesses and spanning the spacebetween said wall members and a clamping element in each recessinterposed between a side edge of the base member and an end of therecess and securing the base member in the recess by forcing theopposite edge of the base member against the other end of the recess.

11. The invention according to claim 10, wherein the said opposite endof the recess is undercut and the adjacent edge of the base is beveledto engage in the undercut and wherein the said one edge of the basemember is beveled and the clamp member adjacent thereto has a beveledend engaging against the adjacent beveled edge of the base.

12. The invention according to claim 9, wherein said electrodesupporting base has a top surface provided with electrolyte drainagegutters lying on opposite sides of the carbon body electrode.

13. The invention according to claim 9, wherein said spaced bodies andthe slide bar upon which the bodies are supported have a tongue andgroove coupling one with the other whereby to facilitate movement of atleast one of the pair of bodies in a straight path along the slide bar.

References Cited in the file of this patent UNITED STATES PATENTS312,384 Richter Feb. 17, 1885 1,324,044 Harris Dec. 9, 1919 2,884,853Cantoni May 5, 1959 2,943,562 Phillips July 5, 1960 OTHER REFERENCESMarking Precision Parts, Bulletin of the Lectroetch Company, 1727 DoanAve., Cleveland 12, Ohio (1943) (two sides).

1. IN APPARATUS FOR ELECTROLYTICALLY ETCHING METAL BY USE OF ANELECTROLYTE MOISTENED STENCIL CHARACTER CARRYING TAPE LYING ACROSS THETOP OF A CARBON ELECTRODE FROM WHICH ELECTRIC CURRENT IS CAUSED TO PASSTHROUGH THE STENCIL TAPE TO A METAL BODY LYING THEREON, SPACED CLAMPINGMEANS EACH FORMED TO PROVIDE COOPERATING JAWS FOR GRIPPING AN END OF AFLEXIBLE STENCIL TAPE LYING ON AND ACROSS THE ELECTRODE, SAID MEANSBEING RELATIVELY ADJUSTABLE FOR DRAWING THE TAPE TO A TAUT CONDITION,MEANS FOR MOISTENING THE TAPE IN THE PART THEREOF LYING ON THEELECTRODE, AND MEANS FOR RECIPROCABLY RECTILINEARLY MOVEING SAIDCLAMPING MEANS AND TAPE RELATIVE TO THE ELECTRODE FOR SELECTIVELYPOSITIONING STENCIL CHARACTERS ON THE TAPE RELATIVE TO THE TOP OF THEELECTRODE, WHEREBY AN OPERATOR''S HANDS MAY BE KEPT FREE FOR POSITIONINGA METAL BODY UPON THE TAPE AND ELECTRODE FOR STENCILING AND ALSO KEPTFREE OF CONTACT WITH THE ELECTROLYTE.